Traas A.M., Abbott B.L., French A., et al.
J Vet Intern Med, 2008. 22(6): p.1427-31.
Two male littermate kittens (Kitten A and B) were examined at 14 weeks of age because of straining to defecate in the litter box. According to the owner neither kitten was seen having a bowel movement during the prior 2 weeks, but they were still eating, drinking, and urinating appropriately.